Stackable cup



FIG. 1 is a top perspective view of a stackable cup showing my new design;

FIG. 2 is another top perspective view thereof;

FIG. 3 is a bottom perspective view thereof;

FIG. 4 is a side elevational view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines showing of environment in FIGS. 1, 2 and 4 are for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a stackable cup, as shown and described. 